Retractable composite  rotor blade assembly

ABSTRACT

A retractable rotor blade assembly includes a rotor hub assembly having a rotor hub wall, a pitch disc mounted to the rotor hub wall for undergoing rotation about a longitudinal axis, and retractable rotor blades configured to be extended and retracted relative to the rotor hub assembly. Each of the rotor blades has an interlink assembly, a blade base, and a damper for dampening movement of the interlink assembly during extension and retraction of the rotor blade. The interlink assembly includes a plurality of interconnected link base subassemblies each configured to be translated along a span of the rotor blade such that each subsequent link base subassembly becomes stacked one atop the other while remaining connected to a next link base subassembly. The blade base is interconnected between the pitch disc of the rotor hub assembly and one of the interconnected link base subassemblies.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/892,139, filed May 10, 2013, which is a continuation of U.S. patentapplication Ser. No. 12/582,889, filed October 21, 2009, now U.S. Pat.No. 8,459,948, which claims priority benefit of U.S. Provisional PatentApplication No. 61/108,282, filed Oct. 24, 2008, all of which areincorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates primarily to the field of aerospace andthe field of lift generating structures. More specifically, theinvention relates to the design of retractable rotor blades for a rotorblade assembly used to produce lift and thrust for vertical and shorttake off vehicles.

2. Description of the Related Art

Rotor blades have been used for many years to achieve flight. Ashortcoming of the related art is that conventional rotor blades androtor blade assemblies have longitudinally rigid structures (U.S. Pat.No. 7,475,847). Many rotor blades are now made of carbon fiber, fiberglass and other composite materials. These conventional composite rotorblades and composite rotor blade assemblies are manufactured to be usedas rigid structures, not capable of being collapsed to a smaller volume(U.S. Pat. No. D 580,344). In order to be effective, conventional rotorblades often require very large rotor blade spans. Large rotor bladescustomary in VTOL (vertical take-off and landing) and STOL (shorttake-off and landing) vehicles typically require large storage space tohouse them.

In other examples of the related art, rotor blades are designed toreconfigure into a more stowable state (U.S. Pat. No. 6,176,679). Thisis often because they are to be housed indoors when not in use, or as anattempt to reduce the breadth of the rotor blade's slipstream whentransported. Another example of the related art is the ability for somerotor blades to be capable of folding onto themselves (U.S. Pat. No.4,086,025). Another example of the related art is the ability for somerotor blades to be retracted using a telescoping system (U.S. Pat. No.6,972,498). The aforementioned example is made retractable by concentrictelescoping solid rotor blade cross sections. A shortcoming oftelescopically retracted systems is that they require each subsequentsection of the rotor blade to be of a different dimension than thepreceding one. This reduction of dimension and non-uniformity of theblade sections creates aerodynamic instabilities and it is notdesirable.

Since the development of the airplane there have been many attempts tocombine the ability of a flying vehicle with that of an automobile (U.S.Pat. No. 7,481,290). One particular example of such a vehicle hasfolding wings (U.S. Pat. No. 7,462,015). Another vehicle examplerequires the user to completely remove the lifting surfaces from thevehicle when being used as an automobile. Other examples of the relatedart incorporate road vehicles equipped with full scale aircraft wings.Other examples of the related art use rotor blades which fold uponthemselves (U.S. Pat. No. 7,584,923). These designs are too cumbersomeand do not provide the required compactability of the rotor blades to beused practically by road worthy vehicles. Some examples of the relatedart use fan blades to generate lift, but these require the fan blades tobe operated at higher rpm. The requirement for higher rpm is due mainlyto the small dimensions of the fan blades. Another example of therelated art use fabrics as the exterior surface of the blade which isexposed to the airstream (U.S. Pat. No. 4,411,398).

Other objects and advantages of the present invention will becomeapparent from the following descriptions, taken in connection with theaccompanying drawings, wherein, by way of illustration and example,embodiments of the present invention are disclosed.

SUMMARY OF THE INVENTION

In accordance with preferred embodiments of the invention, a retractablecomposite impeller (rotor blade) assembly is described herein. Theprimary difference between the present invention and the related art isthat conventional rotor blades and rotor blade assemblies havelongitudinally rigid blades. Furthermore, unlike telescopicallyretracted systems, the present invention does not require eachsubsequent section of the rotor blade to be of a different dimensionthan the preceding one. The present invention also does not restrict thelength of the rotor blade. The current invention allows for controlleddynamic deployment of rotor blades. The present invention also increasesthe speed and precision with which the rotor blades can be retracted anddeployed. The present invention makes it possible to make retractablefan blades.

The present invention includes major and minor components, assembliesand subassemblies arranged such that together they form a mutuallyreinforcing structure capable of being deployed to generate the requiredforces for flight and of being retracted to a considerably smallervolume when not in use or stored. According to the present invention, avehicle equipped with the current invention will be capable of verticaltakeoff and landing. In its retracted state, the current invention willmake it possible for the vehicle to travel along automobile roads ofstandard dimension. The constituent components and subassemblies of thepresent invention may comprise multiple instances of similar ordissimilar materials and employ the most desirable characteristics ofeach material.

Due to improvements made in the area of composite materials, the presentinvention employs these materials to create retractable rotor bladeswhich do not require manual manipulation or removal of any part of therotor blade assembly (also referred to herein as a rotor system) inorder to work. By using flexible and strong composite materials to bearthe primary stresses during operation, the present invention reduces theloads experienced by the remaining rigid support structure andconsequently reduces the amount of creep experienced by the rotorsystem. Composite materials are exceptionally well suited at resistingtensile stresses and as such are ideal materials for this application.Typical composite materials include, but are not limited to, carbon andglass fibers, elastomers, aramids and other high strength polymers.Another advantage of the rotor blades of the present invention is itsability to be refitted or refurbished with very little modification andlimited part replacement. In other words, if the exterior layers of thepresent invention are damaged they can be easily replaced withoutneeding to replace the entire rotor system and at a considerably lowercost than conventional rotor blades.

The primary components and assemblies of the of the rotor blade assemblyaccording to the present invention may include a rotor hub assembly, arotor axle assembly, a retracting reel assembly, a blade internalsupport structure, a release cable assembly, a helical ribbon assemblyhaving helical wound ribbons, an exterior sleeve assembly having aflexible sleeve, a blade casing assembly, and an extendable zippermechanism. A rotor axle serves as an axis of rotation and to transmittorque to the retractable composite rotor blade assembly. The purpose ofthe rotor blade assembly is to generate lift when in operation. Therotor hub assembly provides a structure onto which the rotor bladeassembly is connected. The rotor hub assembly includes a rotor hub thathouses a pitch disk through which torque is transmitted to the rotorblade assembly such that the angle of attack of the rotor blade assemblyis able to be altered.

The components of the rotor blade assembly have a characteristicaerodynamic profile and/or are capable of conforming to such a profile.The rotor blade assembly may also include a blade base and an interlinkbase assembly. The purpose of the blade base is to connect the rotor hubto the interlink base assembly. In one possible embodiment of theinvention, the purpose of the interlink base assembly is to form a rigidstructure over which the flexible sleeve can be fitted. In a secondpossible embodiment of the invention, the interlink base assembly isalso fitted with a plurality of the helically wound ribbons. The purposeof the helically wound ribbon is to reinforce the interlink baseassembly and form a rigid structure over which the flexible sleeve canbe fitted. Another purpose for the helically wound ribbon is toconstrict, lock and rigidify the interlink base assembly when it is inuse and allow the interlink base assembly to retract when not in use.

The interlink base assembly may include a plurality of link basesubassemblies. In one possible embodiment of the invention, each linkbase subassembly comprises a rigid aerofoil shaped cross section andmechanical linkages. In a second embodiment of the invention, each linkbase subassembly also includes hinged plates. Each link base subassemblyis mechanically connected to another link base subassembly throughlinkages to form a longitudinally connected structure capable of beingstacked one atop the other. The rigid aerofoil shaped cross sections arestacked one atop the other and mechanically connected to allow them toseparate while remaining one assembly. Each link base subassembly isequipped with a locking mechanism in order to ensure rigidity of theentire interlink base assembly when deployed. Each locking mechanism canbe activated independently or simultaneously by a release cable. Therelease cable is part of the retraction assembly which is housed in therotor hub.

In another possible embodiment of the invention, the flexible sleevecomprises elastic ribs, an elastic and flexible skin and an elasticsling membrane. In a second possible embodiment of the invention, theflexible sleeve can include a resealable elastic trailing edge. Thepurpose of the flexible sleeve is to be the outer most layer of therotor blade assembly and, as such, it is exposed to the airstream. Theflexible sleeve also serves to reinforce the rotor blade assembly andprovide a smooth exterior surface for the rotor blade assembly. Theflexible sleeve may be constructed of woven, braided or elastomericmaterial to form a covering for the cross sections and mechanicallinkages of the interlink base assembly. In a second embodiment of theinvention, with the use of the elastic trailing edge the rotor bladeassembly is equipped with an extendable zipper mechanism. The purpose ofthe extendable zipper mechanism is to separate and also to reseal anupper and a lower section of the elastic trailing edge. The purpose ofthe blade base casing is to house the rotor blade assembly when stowed.It is to be understood that the present invention can also be used toform a wing, that is to say, it can be easily modified to be used as awing of an airplane.

BRIEF DESCRIPTION OF THE DRAWINGS

Definition of Orientation:

The drawings of the invention have been illustrated in agreement withthe preferred embodiment of the invention. The figure numbers labeledthroughout this document are located below the figures they refer to.

FIG. 1 is a top view of the rotor blade assembly in its extendedcondition comprising three rotor blades;

FIG. 2 is a top view of the rotor blade assembly in its retractedcondition showing the internal assembly components of one of the rotorblades;

FIG. 3 is a top view of the rotor blade assembly showing the majorassemblies which are common to each rotor blade and have been shown hereindividually for clarity;

FIG. 4 is a top view of the rotor blade assembly in its retractedcondition showing the major assemblies which are common to each rotorblade;

FIG. 5 is a perspective view of the rotor blade assembly showing theinternal components of the rotor hub and showing the internal componentsof the major assemblies which are common to each rotor blade;

FIG. 6 is a perspective view of the rotor blade assembly showing releasecables;

FIG. 7 is a perspective view of a recoiling (retraction) reel assemblyand showing outlines of pitch discs;

FIG. 8 is a perspective view of the rotor blade assembly showingoperation of the major assemblies in their retracted condition;

FIG. 9 is an isometric view of one of the rotor blades in its retractedcondition showing hinge connections between the blade casings to the hubwall and a zipper slider mechanism;

FIG. 10 shows a pair of end tabs arranged such that they do notinterfere with each other during retraction and showing one possibledirection of the torsional spring force;

FIG. 11 is an isometric view of a retractable internal skeleton showingmajor components with several hinged plates removed to show internalcomponents;

FIG. 12 is a perspective view of a link base subassembly showing themajor components;

FIG. 13 is a partial, top, perspective view of the link base subassemblyshowing components and function of the internal locking mechanism andrelease cables;

FIG. 14 is an isometric front view of a link base hub;

FIG. 15 is an isometric back view of the link base hub;

FIG. 16 is an isometric view of the interlink assembly in its retractedcondition showing the mechanical operation of retractable links;

FIG. 17 is an isometric front view of the link base hub showing the hubledge;

FIG. 18 is an isometric rear view of the link base hub showing the hubledge and pneumatic dampener in their collapsed condition;

FIG. 19 is a partial top cross-sectional view of the internal componentsof one rotor blade showing the components which act to retract the rotorsystem;

FIG. 20 is a partial side cross-sectional view of the rotor bladeassembly showing the mechanical arrangement of the retraction assemblyincluding release cables in the extended condition;

FIG. 21 is a side view in partial cross-section of the rotor bladeassembly showing the location of the zipper slider mechanism when therotor system is retracted;

FIG. 22 is an isometric front view of the internal skeleton wrapped bythe helically wound ribbon;

FIG. 23 is a view normal to the span of the lifting body showing across-section of the rotor blade and showing the characteristicaerodynamic linkage of the lifting body;

FIG. 24 is an isometric view of the construction of the flexible sleeve,elastic membrane and zipper closure showing how they are joined;

FIG. 25 is an isometric view of the flexible sleeve in its retractedcondition showing an additional embodiment of the elastic membrane;

FIG. 26 is an isometric trailing edge view of the elastic skin showing arepresentation of the composite fiber helical weave pattern;

FIG. 27 is a trailing edge view of the elastic skin showing arepresentation of a composite fiber weave pattern and buckling patternof the elastic trailing edge;

FIG. 28 is an isometric view of the end cap of elastic trailing edgeshowing hook and hollow geometry;

FIG. 29 is an enlarged partial cross-sectional view of a pin connectionbetween the helically wound ribbon and internal skeleton;

FIG. 30 is an enlarged isometric view of the elastic trailing edge endcap showing the tongue and groove geometry;

FIG. 31 is an enlarged isometric view of tongue and groove geometry;

FIG. 32 is an isometric rear view of the configuration of the zippertooth closure and zipper slider function;

FIG. 33 is a front axial view of a zipper slider of the invention;

FIG. 34 is a rear axial view of the zipper slider of the invention;

FIG. 35 is a side view of the zipper slider of the invention;

FIG. 36 is a front axial view of another embodiment of the zipper sliderof the invention showing the zipper slider ring bearing;

FIG. 37 is a rear axial view of another embodiment of the zipper sliderof the invention showing the zipper slider ring bearing;

FIG. 38 is an isometric trailing edge view of the elastic skin showingthe composite construction of a rib-reinforced polymer matrix in theshape of an airfoil; and

FIG. 39 is a top view of the rotor blade assembly showing the bladebase.

DETAILED DESCRIPTION OF THE INVENTION

A technical description of the major subassemblies of the invention willfollow.

Rotor Blades

Referring to FIG. 1 and FIG. 2, the retractable composite impeller(rotor blade) assembly embodiment comprises a plurality of rotor blades02 (three in this embodiment) as depicted. FIG. 1 also shows theretractable composite rotor blade assembly of a first preferredembodiment comprising the major subassemblies and in its fully extendedcondition. The geometry of a rotor hub assembly 10 corresponds to thenumber of rotor blades 02. In this configuration, each rotor bladeassembly 02 experiences the same centripetal force during rotation anddeceleration.

Referring to FIG. 1 thru FIG. 4, the major subassemblies of the rotorblade assembly of the present invention work in concert to allow eachrotor blade 02 to have the ability to become extended when the rotorsystem is rotated, and contracted when the rotor system is forced tocome to rest and in a controlled manner by way of a retracting reelassembly 13. The primary subassemblies interface with each other in sucha way that they transmit the loads developed during rotation and act toreinforce each other thereby strengthening the rotor system as a whole.

Referring to FIG. 3 and FIG. 4, each rotor blade 02 comprises identicalcomponents and subassemblies with the exception of components andsubassemblies of rotor blade 02 which are shared by way of rotor hubassembly 10 and retraction or retracting reel assembly 13. Referring toFIG. 1 thru FIG. 4 and FIG. 11, the major assemblies which make up therotor blade assembly of the present invention are the rotor hub assembly10 having within it the retracting reel assembly 13, an interlinkassembly 11 which comprises a blade base 30 and a plurality of link basesubassemblies 12 and is connected to an exterior of a rotor hub wall 20of rotor hub assembly 10, a helical ribbon assembly 14 which is wrappedaround the interlink assembly 11, a flexible and elastic sleeve 15 whichenvelopes both the helical ribbon assembly 14 and the interlink assembly11, and a zipper slider mechanism 16 which encompasses the flexible andelastic sleeve 15 and serves to open and close a closure located at atrailing edge of the flexible and elastic sleeve 15.

Several components of the present invention are standard mechanicalparts which are ubiquitous. These standard parts include helical springs03, torsion springs 04, bolts and screws 05. Their usages throughout theinvention is apparent to anyone skilled in the art related to thepresent invention. Standard parts which share the same label areinstantiated throughout the various subassemblies of the invention.Wherever they are referenced it is to convey that they perform the sametype of function and can be used in different locations.

The retraction reel assembly 13 is mechanically connected to componentswhich make up the rotor blade assembly. With additional reference toFIG. 20, when the rotor system is rotated about an interior rotor axle72 defining a central axis or axis of rotation, a centripetal force isdeveloped about the central axis which forces the components which arefree to move to be extended radially outward from the axis of rotation.When the rotor system is brought to rest by the retraction reel assembly13 which includes a breaking actuator 73, each component of the rotorblade 02 which is connected to the retraction reel assembly 13 by way ofrelease cables 70 is pulled radially inward towards the central axis.This is the primary operation which enables the rotor system to beextended or retracted.

Rotor Hub Assembly

The rotor hub assembly 10 serves as the main structure to which eachrotor blade 02 is connected. It also houses the retraction reel assembly13 (FIGS. 3-5) which, as further described below, includes an exteriorrotor axle 71, the interior rotor axle 72 (FIG. 20-21) and the breakingactuator 73 (FIG. 21), where the exterior and interior rotor axles 71,72 share the same rotation and impart torque to the entire rotor system.The rotation of breaking actuator 73 is allowed to be neutral when notengaged. Referring to FIG. 5 thru FIG. 9, the rotor hub assembly 10comprises a rotor hub wall 20 which has at its upper edge a hinged topcasing 21 and has at its bottom edge a hinged bottom casing 22. Therotor hub wall 20 also has through it a pitch disc 23. Pitch disk 23 isable to rotate about its longitudinal axis and has a moment arm 25, andconnected to the moment arm 25 is a push rod 24. The rotor hub assembly10 also has a top casing 26 and a bottom hub casing 27. Referring toFIG. 6, FIG. 8, FIG. 9 and FIG. 11, one extremity of push rod 24 isconnected to the pitch disc 23 by a ball and socket connection throughmoment arm 25, and the other extremity of push rod 24 may be connectedto a rotating swash plate. As push rod 24 is moved up or down it causesthe pitch disc 23 to rotate. The rotation of the pitch disc 23 istransmitted to the interlink assembly 11, thereby changing the angle ofattack of the rotor blade 02. When the rotor system is retracted, theelastic and flexible sleeve 15 is stowed within top and bottom hingedcasings 21 and 22.

Referring to FIG. 7 and FIG. 19, pitch disc 23 has a circular groovewhich allows it to be held in place by rotor hub wall 20 while remainingfree to rotate along its longitudinal axis. Pitch disc 23 and blade base30 are axially coincident and have a common faying surface by which theyare rigidly or mechanically connected. Referring to FIGS. 9 and 20, tophinged casing 21 and bottom hinged casing 22 are connected at the bottomand top edges of the rotor hub wall 20 by means of hinge connections 28,29. The purpose of exterior and interior rotor axles 71, 72 (FIG. 21) isto provide torque to the retractable composite rotor assembly of thepresent invention.

Referring to FIG. 19 thru FIG. 21, the casings 21 and 22 are opened andshut by means of hinged connections to the rotor hub wall 20. Uponrotation of the rotor system, each hinged casing 21 and 22 is affectedby the centripetal force of rotation and is caused to be shut in theconfiguration shown in FIG. 20. Upon deceleration, a potential springforce located at the hinged connections to the rotor hub wall 20 causethe hinged casings 21 and 22 to return to their opened configurationshown in FIG. 21. The hinged casings 21 and 22 serve two majorfunctions. They serve to stow the retracted rotor blade assembly and toengage the zipper slider mechanism 16 which contributes to thecollapsibility of the rotor system. Activation of the zipper slidermechanism 16 is made possible by each hinged casing 21 and 22 beingsimultaneously hinge connected to the rotor hub wall 20 and to hingedplates 116 and 117 of the zipper slider mechanism 16. When the hingedcasings 21 and 22 are rotated about their connection to the rotor hubwall 20, a rotation about hinge connections 28 and 29 is also developedwhich then causes translation of a main zipper slider 110 of the zipperslider mechanism 16, as further described below with reference to FIGS.33-35. Mechanical springs can also be located at hinge connections 28and 29 to assist the operation of the zipper slider mechanism 16.

Interlink Assembly

Referring to FIGS. 10, 11, 12, 15, 19, 23 and 39, the interlink assembly11 comprises the blade base 30 having a plurality of pin joints 31,guide notches 34, blade base rectangular slots 35, a thru hole 38, and acharacteristic profile 32. The interlink assembly 11 further comprises apneumatic damper and cable casing 33 having a collapsible corrugatedgeometry 36 and a slotted cylindrical section 37, and a plurality oflink base subassemblies 12 which are repeated similar to links in astandard chain.

Referring to FIG. 11, the interlink assembly 11 can be thought of as achain comprising of a base connected to repeating links, where eachrepeating link is referred to and corresponds to one of the link basesubassemblies 12. Referring to FIG. 11 thru FIG. 18 and FIG. 39, at oneextremity blade base 30 is mechanically connected to pitch disc 23 andat its other extremity is interconnected to a first link basesubassembly 12 by way of rectangular base slots 35 and hub hinges 50 offirst link base subassembly 12. In other words rectangular base slots 35located at one extremity of blade base 30 serve as sockets for hubhinges 50 which are part of first link base subassembly 12. The linkbase subassembly 12 is the fundamental structure which forms theinterior structure of the rotor blade 02, where one end of a first linkbase subassembly 12 is connected to the blade base 30 and the other endof the link base subassembly 12 is interconnected to a next link basesubassembly 12. Referring to FIGS. 5, 11, 22, 23 and 39, the interlinkassembly 11 forms a retractable internal support frame or internalscaffolding for the helical ribbon assembly 14 and flexible and elasticsleeve 15 such that when both the helical ribbon assembly 14 andflexible and elastic sleeve 15 envelope the interlink assembly 11 andare in their extended conditions, they form a rigid assembly with acharacteristic airfoil profile.

Referring to FIGS. 12, 13, 17 and 18, the pneumatic damper 33 has twomajor features which enable its function: a collapsible section 36 witha corrugated geometry and a slotted cylindrical section 37. The slottedcylindrical section 37 has two notches which allow release cable 70 topass through these notches and be connected to two locking arms 45 whichare housed within a link base hub 40 of link base subassembly 12. Theslotted cylindrical section 37 of damper 33 is clasped within link basehub 40, thereby ensuring that during extension or retraction of therotor system only the corrugated section of the damper is collapsed orelongated. The pneumatic damper and cable casing 33 serves two majorpurposes. It serves as a cable housing for release cable 70 and as adamper which opposes the motion of interlink assembly 11 when it isextended or retracted. This allows for a more smooth deployment of therotor blades. The pneumatic dampener 33 can also serve as an elasticspring.

Referring to FIG. 4, FIG. 8, FIG. 9, FIG. 12, FIG. 16 and FIG. 20,retractability of the rotor system is achieved when each link basesubassembly 12 is translated along the span of the rotor blade such thateach subsequent link base subassembly 12 becomes stacked one atop theother while remaining connected to the next link base subassembly 12.This is achieved by way of retractable links 46 and 47 of the base linksubassembly 12. In other words retractable links 46 and 47 are the meansby which each subsequent link base subassembly 12 is interlinked. Thisis accomplished by way of hinged connections between link hinges 57 tohinges 50 of link base hub 40 and by passing linkages 46 and 47 throughslotted openings 55 of a second link base subassembly 12 as shown inFIGS. 15 and 16. In accordance with a preferred embodiment of theinvention, upon retraction interlink assembly 11 reconfigures from theconfiguration shown in FIG. 3 to the configuration shown in FIG. 4 andin both states remains one interconnected assembly.

Link Base Subassembly

Referring to FIGS. 11-18, the link base subassembly 12 comprises a toplink hub 41 which has a slotted pin joint 51, and a bottom link hub 42.The link hub 41 and link hub 42 together form the link base hub 40 whichhas a characteristic airfoil profile 32 and is provided with a throughhole 43, a hub ledge 59, link head grooves 53, hub hinges 50, slottedsocket openings 55, threaded screw holes 56, the two locking arms 45,and a plurality of plate hinge sockets 58; The link base subassembly 12further comprises a first retractable link 46 and a second retractablelink 47 both provided with a curved profile 48, locking ledges 49, linkheads 52, and link hinges 57. The link base subassembly 12 furthercomprises a plurality of hinged plates 44 which are hinged to link basehub 40 by way of hinged connections between plate hinges 54 and platehinge sockets 58.

Referring to FIG. 13 thru FIG. 18, the link base hub 40 is shown to beformed of two sections, a section corresponding to the top link hub 41and which forms the top of the airfoil profile 32, and a sectioncorresponding to the bottom link hub 42 and which forms the bottom ofthe airfoil profile 32, the top and bottom link hubs 41, 42 being heldtogether by way of screw holes which also serve to fasten a lockingmechanism 60. Retractable links 46 and 47 are allowed to slide withinlink base hub 40 by way of slotted socket openings 55 and are preventedfrom sliding out during rotation by way of mechanical interferencebetween link head grooves 53 and link heads 52. In this way, amechanical linkage is formed and retractable links 46 and 47 are allowedto slide within the limits of the slotted socket opening 55. Referringto FIG. 12 and FIG. 13, the curved profile 48 of retractable links 46and 47 serve two major purposes: one is to resist the torsionexperienced by interlink assembly 11 during operation, and the other isto guide retractable links 46 and 47 outward during retraction to avoidinterference with subsequent link base subassemblies. Link hinges 57 maybe loaded with torsional springs to provide torque to the retractablelinks 46 and 47 in the direction shown in FIG. 13. This encourages eachretractable link to pivot outward during retraction.

Each hinged plate 44 is hinged to link base hub 40 by way of plate hingesockets 58 and plate hinges 54. Each hinged plate 44 extends from itshinged edge located on a first link base hub 40 to a next link base hub40 such that its other unhinged edge rests on hub ledge 59 of the nextlink hub 40. Referring now to FIG. 12 thru FIG. 18, hinged plates 44 arehinged such that they form the shape of an airfoil surface while rotorblade 02 is extended and when the rotor blade 02 is retracted overlapone another like shingles.

The operation of locking mechanism 60 is described with reference toFIG. 12 and FIG. 13. Threaded screws holes 56 also serve as pin jointsabout which locking arms 45 are allowed to pivot. This is how thelocking arms 45 are able to be rotated to the unlocked position. Themechanism 60 is locked by mechanical interference between locking ledge49 located on retractable links 46 and 47 and the distal edge of lockingarms 45. Locking pin joints 61 may be fitted with torsional springswhich can be used to impart a permanent torque to locking arms 45 asshown in FIG. 13. This will ensure that the rotor blade system defaultsto the locked position. Release cable 70 is connected to locking arms 45such that translation of release cable 70 causes locking arms 45 torotate about locking pin joints 61, thereby clearing the mechanicalinterference and unlocking the mechanism.

Retraction Reel Assembly

Referring to FIG. 19 thru FIG. 21 and FIG. 39, the retraction reelassembly 13 can be thought of as concentric shafts where each shaftcontributes to the rotation, deceleration and/or retraction of the rotorsystem. The retraction assembly 13 serves to unlock and retract eachrotor blade 02. The retracting reel assembly 13 comprises an exteriorrotor axle 71, an interior rotor axle 72, and a breaking actuator 73having a plurality of breaking notches 77 located at its exteriorsurface and an actuator chamfer 78 at its upper edge. The breakingactuator 73 is positioned coaxially and in between exterior rotor axle71 and interior rotor axle 72. The breaking actuator 73 is able torotate at a different rate relative to the exterior and interior rotor71 and 72. The retracting reel assembly 13 also comprises a plurality ofrecoiling spools 74 which form a reel cage 75. Each recoiling spool 74has fitted within it a plurality of breaking pins 76, where eachrecoiling spool acts as a bobbin when the retraction (release) cable 70is wrapped around it. Each release cable 70 has one end connected to theedge of a recoiling spool 74 and has the other end passed thru throughhole 38 and is connected to locking mechanism 60 by way of locking arms45. The rotation of reel cage 75 is neutral when not engaged by breakingactuator 73 and is allowed to rotate about the interior rotor axle 72.The reel cage 75 is held within the rotor hub assembly 10 at the top bythe upper part of interior rotor axle 72 and at the bottom by theexterior rotor axle 71.

The motion of the reel cage 75 is allowed to be neutral when the rotorblades are to be extended. Upon spin-up of the rotor system, theretraction reel assembly 13 experiences the same rotational speed as therest of the rotor system by way of the tension imparted by releasecables 70. To initiate retraction of the rotor blades 02, the breakingactuator 73 is translated vertically along its axis of rotation and isrotated at a different rotational speed than the rest of the rotorsystem such that it engages with and depresses the breaking pins 76(FIG. 21). Each breaking pin 76 is fitted with a coaxially locatedhelical spring 03 to provide a reaction force against a surface ofbreaking actuator 73. As breaking actuator 73 is translated upward,breaking pins 76 are guided into breaking notches 77 by way of actuatorchamfer 78. The breaking pins 76 are then forced to translate radiallyoutward while simultaneously being caught in breaking notches 77. Thisaction effectively stops the reel cage 75 which is released from aneutral condition and assumes the rotation of breaking actuator 73. Theaction of recoiling spool 74 also serves to actuate locking mechanism 60in link base hub 40. This action simultaneously unlocks lockingmechanism 60 and develops a net force radially inward which consequentlycauses retractable links 46 and 47 to slide through slotted socketopening 55 and acts to retract the rotor blades inward toward the rotorhub assembly 10. Reel cage 75 and each recoiling spool 74 acts as abobbin onto which release cable 70 is coiled and the rotor blade is thenretracted.

Referring to FIG. 19 thru FIG. 21, each locking mechanism 60 is unlockedby a dedicated instance of release cable 70. One advantage of having adedicated release cable 70 for each locking mechanism 60 is the abilityto selectively unlock an individual locking mechanism 60 by modifyingthe geometry of breaking actuator 73 or the stacking order of recoilingspools 74 of reel cage 75.

Helical Ribbon Assembly

The purpose of helical ribbon assembly 14 is to serve as the primaryaxial and tensile load bearing subassembly and to reinforce theinterlink assembly 11 and form a rigid structure over which a flexiblesleeve can be fitted. Another purpose for the helically wound ribbonassembly 14 is to constrict, lock and immobilize the interlink assembly11 when it is in use and allow the interlink assembly to retract whennot in use. Referring to FIGS. 5, 6, 8, 10, 22 and 29, the helicalribbon assembly 14 comprises a plurality of sequentially overlappedribbons 80 helically wound at an angle to each other in a crisscrossedbraided pattern similar to a Chinese finger lock braid. Each helicallywound ribbon 80 has at one or both ends thereof an end tab 81 and or aplurality of end pins 82. Each helically wound ribbon 80 comprises aplurality of laminated or woven 1 layers each helically wound around theinterlink assembly 11 and held at either extremity by way of pin joints31. Each helically wound ribbon 80 is held to the interlink assembly 12by way of end tab 81 and or end pins 82. In the figures, helical ribbonassembly 14 is connected at one end to the blade base 30 by way of pinjoints 31 and is connected at the other end to one of the link hubassemblies 12 by way of end pin 82. The purpose of end tab 81 is toprovide a strong support to the laminated or woven composite fibers ofthe braided ribbons. This provides strength to the rotor system duringoperation.

By having a crisscrossed braided pattern similar to a Chinese fingerlock braid and being helically wound at an angle to each other, eachbraided ribbon 80 is capable of changing the radial diameter of thehelix which it forms. Upon retraction of the rotor blade 02, helicalribbon assembly 14 is also retracted and recoiled as shown in FIG. 8.Each helical ribbon 80 is sequentially overlapped such that they form avirtually flat uniform surface when the rotor system is in its extendedcondition, and when helical ribbon assembly 14 is retracted, it takesthe profile of concentric spirals at the center of which is theretracted interlink assembly 11. Referring to FIG. 29, one extremity ofhelical ribbon assembly 14 is guided during retraction and deployment byend pin 82, where pin 82 fits in the slotted pin joint 51 of link basehub 40.

In one embodiment, the braided ribbon 80 comprises a high strength fiberlayer sandwiched by two low friction layers. By this construction, aplurality of the braided ribbons 80 are able to slide with low frictionrelative to adjacent ribbons. Referring now to FIG. 10, end tab 81 canbe fitted with a torsional spring such that upon being rotated about pinjoint 31, a torque is developed to restore end tab 81 to its originalposition.

Two end tabs 81 are arranged side by side to illustrate end tab crosssectional geometry 85. End tab cross sectional geometry 85 allows aplurality of end tabs 81 to be overlapped and/or arranged in proximityto each other and remain guided during rotation about pin joints 31 andupon release return to their original positions relative to an adjacentend tabs 81. Consequently, end tab cross sectional geometry 85 alsoensures that each consecutive braided ribbon 80 is retracted relative toan adjacent braided ribbon 80 and is able to recoil without obstruction.

As described below for the flexible an elastic sleeve 15 with referenceto FIG. 24 and FIG. 25, the functions of elastic sling membrane 95 andelastic fiber membrane 96 are to serve as guiding and separatinginterfaces between the components of helical ribbon assembly 14 andflexible and elastic sleeve 15.

Flexible and Elastic Sleeve

Referring to FIG. 24 thru FIG. 32 and FIG. 38, there is shown anembodiment of the flexible and elastic sleeve 15 which comprises aplurality of elastic ribs 101, elastic and flexible skin 90, and theelastic sling membrane 95. In this embodiment, elastic and flexible skin90 is a continuous membrane formed of an elastomeric sheet or series offibers which are laminated or woven and whose fibers are oriented atdiagonals to each other which allow the skin to change its aspect ratiodepending on the direction of the tension applied. In a preferredembodiment, flexible skin 90 is made of a fibrous, elastomeric, braided,and/or woven material, and/or any combination of the aforementionedmaterials to provide a flexible membrane which serves as an exteriorsurface configured to be exposed to the airstream. Elastic and flexibleskin 90 can be made of a plurality of composite layers. These compositelayers can be constructed of braided composite fibers. These braidedcomposite fibers can be woven to take on beneficial patters whichcontribute to the strength and function of the rotor system. FIG. 26 andFIG. 27 show representations of a braided or woven pattern 100 which iscapable of being longitudinally extended to thereby change the aspectratio between the diameter and the longitudinal span of the braided orwoven pattern. By the use of a braided pattern 100, the flexible andelastic sleeve 15 contributes to the constriction experienced byinterlink assembly 11 and by helical ribbon assembly 14 when the rotorsystem is in its extended condition and allows for relaxation andexpansion of the exterior skin when the rotor system is retracted.

Elastic ribs 101 and elastic sling membrane 95 impart rigidity toelastic and flexible skin 90 while themselves being flexible andelastic. Upon retraction, the use of elastic ribs 101 encourageorganized corrugation of flexible and elastic sleeve 15. In other words,due to elastic rib 101, upon being retracted elastic and flexible sleeve15 will be encouraged to ruffle. FIG. 4 and FIG. 8 illustrate interlinkassembly 11, helical ribbon assembly 14 and flexible and elastic sleeve15 in their retracted states. In other words, flexible and elasticsleeve 15 conforms to profile 32 of interlink assembly 11 when the rotorblade is in its extended condition, and when the rotor blade isretracted the flexible and elastic sleeve is able to buckle or ruffle toa predetermined pattern which is able to envelope the retractedinterlink assembly and retracted helical ribbon assembly.

Referring to FIGS. 19, 20, 23, 24, 25 and FIG. 29, a second embodimentof flexible and elastic sleeve 15 is disclosed. The flexible and elasticsleeve 15 comprises flexible and elastic skin 90 which is made up oflaminated or woven composites and has a sleeve lip 97, a sleeve retainerring 92 which holds the sleeve lip 97 onto the blade base 30 andprevents the sleeve lip from sliding off the rotor blade duringrotation, a plurality of elastic trailing edge strips 91, a plurality ofzipper teeth 93 which are spaced along a zipper web 94 such that azipper closure is formed between a top zipper half and a bottom zipperhalf where both halves extend along an upper and lower longitudinal edgeof flexible and elastic skin 90, and elastic sling membrane 95 and/or anelastic fiber membrane 96. Referring to FIG. 23, the zipper teeth areconnected to the zipper web 94 by crimping one edge of the zipper teeth93 along the zipper web 94.

Referring to FIG. 23 and FIG. 24, at a top longitudinal edge and at abottom longitudinal edge of the flexible and elastic skin 90 there isconnected a top and a bottom flexible and elastic trailing edgesubassembly. The flexible and elastic trailing edge subassemblycomprises a plurality of flexible an elastic trailing edge strips 91which are individually laminated or extruded to form longitudinalsections of a rotor blades trailing edge and are fastened along one edgeto each other to form an upper trailing edge and a lower trailing edge.When the rotor blade is in its extended condition and the zipper closureis in its fastened or zipped condition, the aforementioned componentsform a rigid airfoil trailing edge. The trailing edge subassemblies canbe constructed by way of adhering or stitching each correspondinglongitudinal edge of the zipper web 94 to a corresponding longitudinaledge of the elastic skin 90 and to the longitudinal edge of the flexibletrailing edge strips 91, thereby creating a seam which serves as apermanent fastening between them. Each individual layer of the trailingedge subassembly is stiff enough that when stacked together they form arigid structure and are flexible enough that when retracted are able tobuckle and ruffle.

Referring now to FIG. 24, there is an additional embodiment of elasticmembrane 95 which is folded along its length to form a pleated accordionpattern with a top longitudinal edge of the accordion pattern connectedto the longitudinal edge of a top zipper web 94 and at the bottomlongitudinal edge of the accordion pattern connected to the longitudinaledge of a bottom zipper web 94. Referring to FIG. 19, FIG. 24 and FIG.32 the inner face of elastic sling membrane 95 comes in direct contactwith the exterior surface of helically wound ribbon assembly 14 and onits other face comes in contact with the inner surface of the zipperwedge 111. This configuration creates a barrier between the helicalribbon assembly 14 and the main zipper slider 110. In this way elasticmembrane 95 acts as a guiding interface between helical ribbon assembly14 and the zipper closure formed by zipper teeth 93. This allowsflexible and elastic sleeve 15 to buckle over the interlink assembly 11and helical ribbon assembly 14 while retaining its ability to return toits prior condition and shape when the rotor system is extended orretracted. Another use for the elastic membrane 95 is to guide the topand bottom zipper teeth during opening and closing of the zipper systemand also serves to prevent snags, misalignment and interference of thezipper teeth 93.

Referring to FIG. 25, elastic fiber membrane 96 is shown serving thesame function as elastic sling membrane 95 and is shown to be made up offibers oriented one across the other with one extremity of the eachfiber connected to a top zipper web and the other end connected to abottom zipper web. In this way, a webbed matrix which connects the topand bottom sections of the elastic sleeve is formed. Interlocking tongueand groove geometry 98 shown in FIG. 30 and Fig, 31 and hook and hollowgeometry 99 shown in FIG. 28 represent additional possible closure typesfor flexible and elastic sleeve 15.

Zipper Slider Mechanism

Referring now to FIG. 5, FIG. 19, and FIG. 33 thru FIG. 35, the zipperslider mechanism 16 comprises a main slider 110 encompassing flexibleand elastic sleeve 15 and serving as the primary means by which theclosure formed by flexible and elastic sleeve 15 is zipped and unzipped.The major features which enable the main slider's function are a zipperwedge 111 located on the inner surface of the main slider's trailingedge and having a top and bottom wedge track 112 which serve to guidethe zipper teeth 93 during extension and retraction of the rotor blade,a first spring loaded wheel 113 located at the top of the inner surfaceof the main slider 110, a second spring loaded wheel 114 located at thebottom of the inner surface of the main slider 110, a third springloaded wheel 115 located on the inner surface of the main slider'sleading edge where each spring loaded wheel serves to assist in theretraction of the flexible and elastic sleeve 15 by way of a springpotential which is generated during extension of the rotor blades andcaused by mechanical friction between the spring loaded wheels and theexterior surface of the flexible skin 90, a first hinged plate 116having one end hinged to the top of the main slider and the other endhinged to the inner surface of the top rotor casing 21, and a secondhinged plate 117 having one end hinged to the bottom of the main sliderand the other end hinged to the inner surface of the bottom rotor casing22.

The main slider 110 serves the same function as a conventional zipperslider whereby it is translated along the length of the rotor blade 02to open and close the zipper closure created by the flexible and elasticsleeve 15. Referring now to FIG. 20 and FIG. 21, a first hinged plate116 is connected to the top hinged blade casing 21 by way of top hingeconnection 28 and to the main slider 110 by way of top slider hinge 118.The second hinged plate 117 is connected at one end to the blade bottomhinged casing 22 by way of a bottom hinge connection 29 and at the otherend to the main slider 110 by way of a slider bottom hinge 119. When therotor system is at rest and in its retracted condition as shown FIG. 21,upon application of a rotational acceleration to the rotor system thetop and bottom casings 21 and 22 begin to rotate about theircorresponding hinged connections to the hub wall 20. This motion causesthe angles between the hinged plates and the blade casings to be alteredand thereby cause the main slider 110 to be translated along the span ofthe rotor blade.

Referring to FIG. 19 and FIG. 35, spring loaded wheels 113, 114 and 115are equipped with torsion springs whereby extension of the rotor bladeassembly causes the spring loaded wheels to develop a potential to rollthe elastic and flexible sleeve 15 back to its prior condition. Theroller wheels also impart a frictional force to the trailing edge zipperserving to assist in guiding the zipper teeth 93 along the wedge track112, and upon unlocking the assembly and in the absence of a rotationalforce, assisting to return the assembly to its contracted state. FIG. 32shows how spring loaded wheels 113,114,115 and wedge track 112 worktogether to guide zipper teeth 93 during retraction and extension.

Referring now to FIG. 36 and FIG. 37, a second embodiment of the zipperslider mechanism is disclosed. In this embodiment, the main slider 11has a circular exterior profile and is coaxial to and encompassed by acircular ring bearing 121, where the ring bearing 121 is hinged at itsupper and lower extremities to the top and bottom blade casings,respectively. The purpose of the ring bearing is to allow the mainslider to rotate about its longitudinal axis in unison with and inresponse to the rotation of pitch disc 23.

Operation of the Retractable Rotor Blade Assembly

When the engine of the vehicle (aircraft) is energized, the rotor hubassembly 10 rotates and a centripetal force is developed. The rotorblade assembly is expanded by the centripetal force acting on thecomponents which are free to move, that is, the rotor blade is extendedradially outward from the axis of rotation. During the expansion of therotor blade, the following operations occur. The distal tip of the rotorblade starts to extend radially outward and the zipper slider mechanism16 brings the upper and lower trailing edges of the flexible an elasticsleeve's zipper together and thereby closes the zipper as it extendsoutward.

At the same time, during the expansion process the interlink assembly 11along with each link base subassembly 12, through the rotation of theirhinged linkages, are allowed to extend radially outward and engage thelocks in the link base hub 40, through the locking ledge 49 engagingwith the locking arm 45. Also at the same time, the flexible and elasticsleeve 15 and the helical ribbon assembly 14 are extended outward, byway of centripetal force and mechanical connections to the interlinkassembly 11, and develop constricting effect which serves to rigidifythe rotor blade. The combination of the locking mechanism, the elasticsleeve and the zipper system provide a flexural and lateral bendingstiffness and rigidity to the rotor blade which is required for a liftaction on the aircraft.

When the rotational speed of the engine is reduced and the aircraftbegins to be stopped, the centripetal force is reduced and approaches tozero. At the same time, the retraction reel assembly 13 and breakingactuator 73 (components of the rotor blade 02), through the releasecables 70, unlock and pull the interlink assembly radially inwardtowards the central axis 72. Also at the same time, during theretraction process the zipper slider mechanism 16 unzips the flexibleand elastic sleeve as it is being retracted and serves to guide thehelical ribbon assembly 14 back to their retracted conditions. Theseoperation leads to a retracted rotator blade system.

While the foregoing written description of the invention enables one ofordinary skill to make and use what is considered presently to be thebest mode thereof, those of ordinary skill will understand andappreciate the existence of variations, combinations, and equivalents ofthe specific embodiment, method, and examples herein. The inventionshould therefore not be limited by the above described embodiment,method, and examples, but by all embodiments and methods within thescope and spirit of the invention as claimed.

What is claimed is:
 1. A retractable rotor blade assembly for providingvertical lift to a vehicle, the retractable rotor blade assemblycomprising: a rotor hub assembly having a rotor hub wall and a pitchdisc having a longitudinal axis and being mounted to the rotor hub wallfor undergoing rotation about the longitudinal axis; and a plurality ofretractable rotor blades each configured to be extended and retractedrelative to the rotor hub assembly, each of the rotor blades comprisingan interlink assembly including a plurality of interconnected link basesubassemblies each configured to be translated along a span of the rotorblade such that each subsequent link base subassembly becomes stackedone atop the other while remaining connected to a next link basesubassembly, a blade base interconnected between the pitch disc of therotor hub assembly and one of the interconnected link basesubassemblies, and a damper for dampening movement of the interlinkassembly during extension and retraction of the rotor blade.
 2. Aretractable rotor blade assembly according to claim 1; wherein thedamper has a collapsible section with a corrugated geometry and aslotted cylindrical section; and wherein each of the link basesubassemblies has a link hub within which the slotted cylindricalsection of the damper is mounted for ensuring that during extension orretraction of the rotor blade only the collapsible section is collapsedor elongated, a pair of locking arms housed in the link hub for lockingthe rotor blade in the extended state, and a pair of retractable linksby which the link base subassembly is interconnected with another of thelink base subassemblies.
 3. A retractable rotor blade assembly accordingto claim 1; further comprising a helical ribbon assembly for reinforcingthe interlink assembly, the helical ribbon assembly comprising aplurality of sequentially overlapped ribbons each formed of a pluralityof laminated or woven layers, each of the layers being helically woundaround the interlink assembly.
 4. A retractable rotor blade assemblyaccording to claim 3; further comprising a flexible and elastic sleeveconfigured to cover the interlink assembly and the helical ribbonassembly in the extended and retracted states of the rotor blade.
 5. Aretractable rotor blade assembly according to claim 4; wherein theflexible and elastic sleeve has a flexible and elastic skin and aplurality of elastic ribs for imparting rigidity to the flexible andelastic skin.
 6. A retractable rotor blade assembly according to claim4; wherein the flexible and elastic sleeve further comprises top andbottom zipper halves forming a zipper closure; and further comprising azipper slide mechanism having a main zipper slider for undergoingsliding movement to zip and unzip the zipper closure of the flexible andelastic sleeve during extension and retraction of the rotor blade.
 7. Aflying vehicle having the retractable rotor blade assembly according toclaim
 1. 8. An interlink assembly for a retractable rotor bladeconfigured to undergo extension and retraction movement, the interlinkassembly comprising: a plurality of interconnected link basesubassemblies each configured to be translated along a span of the rotorblade such that each subsequent link base subassembly becomes stackedone atop the other while remaining connected to a next link basesubassembly, each of the link base subassemblies having a damperconfigured to dampen movement of the interlink assembly during extensionand retraction of the rotor blade.
 9. An interlink assembly according toclaim 8; wherein each of the link base subassemblies has a pair ofretractable links by which the link base subassembly is interconnectedwith another of the link base subassemblies, a link hub, and a pair oflocking arms housed in the link hub for locking the rotor blade in theextended state.
 10. A flying vehicle having the interlink assemblyaccording to claim
 8. 11. A retraction reel assembly for retracting arotor blade configured to undergo extension and retraction movement, theretraction reel assembly comprising: a pair of rotor axles configured toundergo rotation for imparting a torque to the rotor blade, a breakingactuator disposed coaxially between the rotor axles for undergoingrotation and having a plurality of breaking notches located at anexterior surface of the breaking actuator, and a real cage formed of aplurality of recoiling spools around which respective ones of retractioncables are configured to be wrapped, each of the recoiling spools havinga plurality of breaking pins configured to be guided into the breakingnotches during retraction of the rotor blade.
 12. A flying vehiclehaving the retraction reel assembly according to claim 11.